Why don't u find out:

http://web2.0validator.com/

Thanks for this link. I really want to get into this web 2.0 thing. I think it is high time I did just this.

@omnipotens

Then you and others might find this useful:
http://www.webdesignfromscratch.com/web-2.0-design-style-guide.cfm

Can you gimme a link where I can get web 2.0 started at once?

The link above should suffice. If you follow at least half of the items on that list, you should be good to go. For starters, you could do the following:

1) Have a bold logo
2) Use big san-serif font
3) add "beta" to any new features or headers on your site
4) Use rounded corners for your container DIVs
5) Implement a solution using any of the javascript libraries out there
6) Photo gallery using lightbox
7) On your forms, make sure you are using large text boxes.

@yawa
one more thing
- it should be a community driven website where the content comes mainly from the users "a la " twitter.com twine.com facebook.com wink.com , etc

@mambenanje

Definitely. In general, a web 2.0 website should be developed with the following in mind:
1) Supports social interaction
2) Encourages user participation
3) Enhanced ("rich" user experience (which is where my first list belongs)
4) Open source data

A PDF i read recently basically put it in perspective for me: Basically, whereas web 1.0 was about commerce, web 2.0 is about people.

@ yawa-ti-de

Thanks. I will put that into trial ASAP.